Nick Kyrgios sensationally quits after calling umpire a joke

Nick Kyrgios faces the prospect of another season-ending ban after branding an official "a joke" before sensationally quitting his first-round match at the Shanghai Masters.

The volatile Australian stormed off the court after losing the first set 7-6 (7-5) in a tiebreaker to Steve Johnson, in apparent protest against the umpiring of Irishman Fergus Murphy.

Incredibly, Kyrgios's dramatic walk-off comes a year after he was suspended from the ATP Tour for tanking at the very same tournament in China and leaves his immediate playing future in doubt once again.

The 22-year-old had received two code violations for unsportsmanlike conduct - the first for smashing a ball out of the stadium - and expressed his dismay at Murhpy for copping a point penalty after swearing during the tiebreaker.

Kyrgios was in command of the breaker leading 4-2, only to erupt when he was delayed on serve.

Officials reportedly mistakenly allowed patrons to enter the arena when the two combatants changed ends and, already agitated, Kyrgios exploded.

"This is normal. You wait for 20 minutes to have to serve. Poor officiating by you. You are a joke," he fumed.

"You think this place could not get any more ridiculous, shit like this happens," Kyrgios told his camp.

"What is he doing? ... "

He was also picked up on TV telling his courtside entourage he would stop if he lost the set, which he did.The latest incident left commentators dumbfounded.

"What is it about Shanghai and Nick Kyrgios? Emotions getting the better of him and he's off," one said.

"The next chapter of the Nick Kyrgios career unfolds."

Another commentator weighed in with: "He said if he loses this set, he's retiring. Not happy with some of the decisions the umpire is making regarding controlling the crowd."

When he'd had enough, Kyrgios called Johnson to the net, shook hands and then also shook hands with Murphy without making eye contact.

Runner-up to world No.1 Rafael Nadal in the China Open final, Kyrgios had been making a run towards the season-ending World Tour Finals before handing Johnson a mid-match walkover.

He was sitting 15th in the Race to London, where the top eight players of the year will assemble for the prestigious round-robin event.

But he will now almost certainly come under serious scrutiny from officials for quitting a match at the very same venue where he was accused of not giving his best efforts 12 months ago.

Kyrgios also received two code violations during his loss to Nadal two days ago after losing his cool over an unfavourable line call in the first game of the final.

His rare, possibly even unprecedented, walk-off on Tuesday night prompted immediate criticism from tennis fans on Twitter.

Many fans declared his actions unacceptable, with one asking how Lleyton Hewitt could excuse his behaviour on this occasion after the Australian Davis Cup captain defended Kyrgios's meltdown against Nadal.

Kyrgios did not front the press after his latest episode in Shanghai.

- AAP